package com.gdue.controller;

import com.gdue.commons.R;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.UUID;

/**
 * 文件上传和下载
 */
@RestController
@RequestMapping("/common")
public class CommonController {

    @Value("${reggie.path}")
    private String  basePath;

    /**
     * 文件上传
     * @return
     */
    @PostMapping("/upload")
    public R<String> upload(MultipartFile   file){
        //file是一个临时文件，需要转存到指定位置，不然本次请求后就会删除

        //原始文件名
        String originalFilename = file.getOriginalFilename();
        //截取后缀
        String substring = originalFilename.substring(originalFilename.lastIndexOf("."));

        //使用UUID重新生成文件名，避免文件名重复而覆盖
        String fileName = UUID.randomUUID().toString()+substring;

        //创建一个目录对象
        File dir =new File(basePath);
        //判断目录对象是否存在
        if (!dir.exists()){
            dir.mkdirs();
        }

        try {
            //将临时文件转存到指定位置
            file.transferTo(new File(basePath+fileName));
        } catch (IOException e) {
            e.printStackTrace();
        }
        return R.success(fileName);
    }

    /**
     * 文件下载
     * @param name
     * @param response
     */
    @GetMapping("/download")
    public void download(String name, HttpServletResponse   response){
        try {
        //输入流，通过输入流读取文件内容
            FileInputStream fileInputStream=new FileInputStream(new File(basePath+name));
        //输出流，通过输出流将文件写回浏览器，在浏览器展示图片
            ServletOutputStream outputStream=response.getOutputStream();

            response.setContentType("image/jpeg");

            int len=0;
            byte[]  bytes=new byte[1024];
            while ((len=fileInputStream.read(bytes))!=-1){
                outputStream.write(bytes,0,len);
                outputStream.flush();
            }
            //关闭资源
            outputStream.close();
            fileInputStream.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
